


A big difference goes a long way

by Demothi



Series: shuttles, trains and cassette tapes oh my [1]
Category: Transformers Generation One
Genre: M/M, Oral Sex, Other, Sex, Size Difference, dual sexed, extreme size difference
Language: English
Status: Completed
Published: 2013-05-10
Updated: 2013-05-10
Packaged: 2017-12-11 11:43:30
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 3,542
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/798375
Author URL: https://archiveofourown.org/users/Demothi/pseuds/Demothi
Summary: <blockquote class="userstuff">
              <p>Rumble and Astrotrain have a bet that Rumble can't get Astrotrain off. As happens, things don't go according to plan. (Now with alternate, less squicky, version available)</p>
            </blockquote>





	1. Version 1

**Author's Note:**

> The first chapter uses human words for sexual body parts, the second chapter is a direct edit that has more commonly found fanon words for these parts, this is so if the first squicks you you can have a way to read it without that.

“Go on.” Astrotrain said, one big hand cupping behind Rumble and drawing him closer to the triple-changer’s interface equipment. 

He looked up at everything laid before him, starting at the top. Astrotrain’s cock had to be at least as tall as Rumble was and wide enough around that the cassette didn’t think his hands could touch if he wrapped his arms around the base of it. The monster of a cock barely even tapered from the base to the tip, large and blunt at the end with some heavy, deep ridges in it. Fortunately that wasn’t what he was here about.

Below the cock by a short bit was a generous vagina, the lips of the area thick and plush and coated with a thin layer of lubricants. Astrotrain wasn’t worked up yet so the lubricant was one that normally kept the area coated so that it was never fully dry. The vagina looked at least big enough that he could stick his head and shoulders inside, and more than likely it was at least as deep as Astrotrain’s cock was long. It was Astrotrain’s vagina, and his own loud mouth, that had got him here.

As sure of himself and cocky as he was it shouldn’t have surprised him when he had informed the bemoaning triple-changer that he could get him off by his vagina alone. Very few of the Decepticons were big enough to fit Astrotrain’s vagina without being unsatisfying, and of those even less were interested in the shuttle-train that way. He would back out if he could, but a bet had been made, and there was no slagging way he was going to lose and end up having to dress up in a human female’s outfit and get pictures taken by Reflector. 

“What’s the matter, backing out?” Astrotrain asked, the strange subharmonic of his voice distorting to imply both humor and disgust at the same time.

“No way! I just wanted a good look at what I’ve got to work with.” He said, reaching out and touching one hand to one of the thick outer lips of Astrotrain’s vagina. He rubbed a little up and down before turning his hand, his fingers sliding into the opening between the lips and he kept stroking it for a few moments, adding his other hand to the other side. He let Astrotrain get used to the touch before he started to pull the lips open, he started at the middle but his first goal was up at the top. 

He worked his way up until he found it, the most sensitive node point on the outer area of the vagina. It was like a soft globe the dusky grey color of the vagina lining tinged just a bit pinkish here as the surface was thin and energon flowed closer here. Rumble reached up with a hand, finding the area fit into his hand with some room to spare, he squeezed and rubbed it softly, used to doing this with parts that fit between fingers or he could at least cover completely with his hand.

“I hope that isn’t all you plan on doing, I could do that for myself.” Though he tried to sound like he wanted Rumble to get on with it Astrotrain had just a tinge of moan to his voice to give away the truth. 

“Hold your rpms, either you let me do this my way, or you lose the bet no matter if you get off or not.” He snapped, tightening his grip a little which earned him a discordant hiss. When nothing else came from the triple-changer Rumble returned to what he was doing, moving up to lick and suckle the node point. Even though there was lubricant already there he knew that he was better of to get Astrotrain worked up before he went any deeper, as it would only serve to heighten the pleasure from it all.

A bit of work went into it but soon enough Astrotrain’s fans were kicking in and he was shifting himself open even further, all good signs that he was starting to feel ready to be fucked. Of course Rumble knew that his cock wouldn’t make a difference to the triple-changer, but he had other plans on how to get him off. He slid his hands down and in, past the plump outer lips into the soft, silky inner areas, a thicker lubricant meant to sooth friction starting to build up at the lower edge of the vagina’s opening. He teased the area as best he could but he knew he would have to stop the oral treatment to the node point and switch to just his hands, and other available tools, for inner stimulation. 

Reluctantly he pulled his mouth from the globe, the slow separation of suction creating a wet popping sound as the two parted. Rumble took a glance up at Astrotrain, around the cock he could see that the big shuttle-train had offlined his optics and rested his helm on the wall behind him, his mouth was open and he was darting his tongue out to lick at his lips, one hand languidly stroking his own chest seams. He chuckled softly and returned to work, sliding down to collect some of the thick intercorse lubricant on his hand before reaching up again, this time for an interior node. 

He rubbed around a bit adding his other hand and searching for the area he knew would feel good.

He knew he found it when Astrotrain jerked in surprise and gasped his head snapping up and optics on to look at Rumble in a flabbergasted manner. “What was that?” he asked, his voice projecting his startled amazement.

“That is the talent of Rumble.” The cassette crowed, looking up at Astrotrain with self satisfied smugness. After a moment he realized his larger partner’s expression was not changing. “Wait, you really mean to tell me no one has gotten you off here before?” He rubbed the spot lightly for emphasis. Astrotrain’s optics darkened with lust and need as he shook his head, mutely answering. “Weeell then, you relax, I’ll handle the rest.” a new smugness suffused the cassette, he would be the one to introduce Astrotrain to this particularly strut melting type of climax.

Returning to his work Rumble lightened his touch a little, now aware that the node would be more sensitive than most because of it’s lack of direct contact like this. The lighter touches were clearly getting Astrotrain worked up nice and fast but Rumble wanted to give him more than just an okay climax now, now he wanted to give him a stellar one. Unfortunately his original plan wasn’t going to work out this way, originally he had planned to get Astrotrain going and then modify the output of his piledrivers to act like a vibrator, but he had a feeling the intensity of that constantly on or near this point would have the reverse effect.

He was busy thinking about how to change his plans, and had been touching around in Astrotrain, shifting the focus off and on that node a bit. Unfortunately he wasn’t thinking about other parts of the triple-changer and nearly gasped as he felt a pressure on his back. “Hey watch what you-” He didn’t finish his complaint as he was shoved, face first, into the vagina. Rumble’s first reaction was to squirm and try to get out, but not only was Astrotrain’s hand still there, fingers curled in but landing just short of the sensitive point, but he was also bucking up into the sensation, moaning loudly.

This may not be as bad as it first seemed, he realized, as he righted himself and found his face near that point, easily noticeable from where he was by the different texture the area had. He leaned his head up and back to lick the spot and Astrotrain’s outside movement stopped, but his vagina started to squeeze just a little bit, bringing Rumble within easy access of that spot, he started to lick and suckle at it, just barely scraping his teeth across it every now and again. At the same time he transformed his arms into their piledriver modes and set them to vibrate against the bottom of the vagina, adding extra stimulus.

He heard Astrotrain cry out a strangled sounding “Yes, please-” and he knew he was on the right track. The vagina trembled around him as Astrotrain’s inner workings tried their damndest to add more pressure to both areas. He complied with his piledrivers but Rumble kept his mouth work soft and un-rushed. He could feel the way Astrotrain was shifting from side to side, it made him think of the big triple-changer flinging his face back and forth as he tried to comprehend the pleasure he was feeling. 

Then it happened, everything stilled for just a moment and then tightened even more, trying to hold Rumble in place. Instead the flood of lubricant that crashed into him dislodged the cassette, pushing him back out of the vagina with a soft plop as Astrotrain howled his climax. Rumble looked up and took an instant capture of the moment, Astrotrain bowed up off the berth held up by the top of his helm pressed to the wall and his feet while his hands held a death grip on the edges of the bed, his own cum splattered up his chest while his cock bobbed in place and his vagina tried to squeeze down on nothing with lubricant dripping from it, some glittering on the inside of the thighs. 

Once the triple-changer lowered back down and relaxed some, though aftershocks still shook him he looked down at Rumble and Rumble looked back up at him. “So it was good, huh?” Rumble asked and he nodded, feeling a bit dumb for his lack of ability to iterate just how good. “Well I would be happy to do it again sometime...” the cassette continued, getting a hungry look of interest from Astrotrain “But... only if you help me out here too.” Rumble pointed down to his own cock which had been released as he had watched Astrotrain finish his climax.

Astrotrain just grinned and held out a hand. “That’s a deal.” When the cassette came close he grabbed hold of him and brought him up to his mouth. With just a little encouragement from his tongue he had Rumble’s hips between his lips and was tonguing him as Rumble did thrashing and howling of his own.

This was going to be a good exchange all around, he was sure of it.


	2. Version 2

“Go on.” Astrotrain said, one big hand cupping behind Rumble and drawing him closer to the triple-changer’s interface equipment. 

He looked up at everything laid before him, starting at the top. Astrotrain’s spike had to be at least as tall as Rumble was and wide enough around that the cassette didn’t think his hands could touch if he wrapped his arms around the base of it. The monster of a spike barely even tapered from the base to the tip, large and blunt at the end with some heavy, deep ridges in it. Fortunately that wasn’t what he was here about.

Below the spike by a short bit was a generous valve, the lips of the area thick and plush and coated with a thin layer of lubricants. Astrotrain wasn’t worked up yet so the lubricant was one that normally kept the area coated so that it was never fully dry. The valve looked at least big enough that he could stick his head and shoulders inside, and more than likely it was at least as deep as Astrotrain’s spike was long. It was Astrotrain’s valve, and his own loud mouth, that had got him here.

As sure of himself and cocky as he was it shouldn’t have surprised him when he had informed the bemoaning triple-changer that he could get him off by his valve alone. Very few of the Decepticons were big enough to fit Astrotrain’s valve without being unsatisfying, and of those even less were interested in the shuttle-train that way. He would back out if he could, but a bet had been made, and there was no slagging way he was going to lose and end up having to dress up in a human female’s outfit and get pictures taken by Reflector. 

“What’s the matter, backing out?” Astrotrain asked, the strange subharmonic of his voice distorting to imply both humor and disgust at the same time.

“No way! I just wanted a good look at what I’ve got to work with.” He said, reaching out and touching one hand to one of the thick outer lips of Astrotrain’s valve. He rubbed a little up and down before turning his hand, his fingers sliding into the opening between the lips and he kept stroking it for a few moments, adding his other hand to the other side. He let Astrotrain get used to the touch before he started to pull the lips open, he started at the middle but his first goal was up at the top. 

He worked his way up until he found it, the most sensitive node point on the outer area of the valve. It was like a soft globe the dusky grey color of the valve lining tinged just a bit pinkish here as the surface was thin and energon flowed closer here. Rumble reached up with a hand, finding the area fit into his hand with some room to spare, he squeezed and rubbed it softly, used to doing this with parts that fit between fingers or he could at least cover completely with his hand.

“I hope that isn’t all you plan on doing, I could do that for myself.” Though he tried to sound like he wanted Rumble to get on with it Astrotrain had just a tinge of moan to his voice to give away the truth. 

“Hold your rpms, either you let me do this my way, or you lose the bet no matter if you get off or not.” He snapped, tightening his grip a little which earned him a discordant hiss. When nothing else came from the triple-changer Rumble returned to what he was doing, moving up to lick and suckle the node point. Even though there was lubricant already there he knew that he was better of to get Astrotrain worked up before he went any deeper, as it would only serve to heighten the pleasure from it all.

A bit of work went into it but soon enough Astrotrain’s fans were kicking in and he was shifting himself open even further, all good signs that he was starting to feel ready to be fucked. Of course Rumble knew that his spike wouldn’t make a difference to the triple-changer, but he had other plans on how to get him off. He slid his hands down and in, past the plump outer lips into the soft, silky inner areas, a thicker lubricant meant to sooth friction starting to build up at the lower edge of the valve’s opening. He teased the area as best he could but he knew he would have to stop the oral treatment to the node point and switch to just his hands, and other available tools, for inner stimulation. 

Reluctantly he pulled his mouth from the globe, the slow separation of suction creating a wet popping sound as the two parted. Rumble took a glance up at Astrotrain, around the spike he could see that the big shuttle-train had offlined his optics and rested his helm on the wall behind him, his mouth was open and he was darting his tongue out to lick at his lips, one hand languidly stroking his own chest seams. He chuckled softly and returned to work, sliding down to collect some of the thick intercorse lubricant on his hand before reaching up again, this time for an interior node. 

He rubbed around a bit adding his other hand and searching for the area he knew would feel good.

He knew he found it when Astrotrain jerked in surprise and gasped his head snapping up and optics on to look at Rumble in a flabbergasted manner. “What was that?” he asked, his voice projecting his startled amazement.

“That is the talent of Rumble.” The cassette crowed, looking up at Astrotrain with self satisfied smugness. After a moment he realized his larger partner’s expression was not changing. “Wait, you really mean to tell me no one has gotten you off here before?” He rubbed the spot lightly for emphasis. Astrotrain’s optics darkened with lust and need as he shook his head, mutely answering. “Weeell then, you relax, I’ll handle the rest.” a new smugness suffused the cassette, he would be the one to introduce Astrotrain to this particularly strut melting type of climax.

Returning to his work Rumble lightened his touch a little, now aware that the node would be more sensitive than most because of it’s lack of direct contact like this. The lighter touches were clearly getting Astrotrain worked up nice and fast but Rumble wanted to give him more than just an okay climax now, now he wanted to give him a stellar one. Unfortunately his original plan wasn’t going to work out this way, originally he had planned to get Astrotrain going and then modify the output of his piledrivers to act like a vibrator, but he had a feeling the intensity of that constantly on or near this point would have the reverse effect.

He was busy thinking about how to change his plans, and had been touching around in Astrotrain, shifting the focus off and on that node a bit. Unfortunately he wasn’t thinking about other parts of the triple-changer and nearly gasped as he felt a pressure on his back. “Hey watch what you-” He didn’t finish his complaint as he was shoved, face first, into the valve. Rumble’s first reaction was to squirm and try to get out, but not only was Astrotrain’s hand still there, fingers curled in but landing just short of the sensitive point, but he was also bucking up into the sensation, moaning loudly.

This may not be as bad as it first seemed, he realized, as he righted himself and found his face near that point, easily noticeable from where he was by the different texture the area had. He leaned his head up and back to lick the spot and Astrotrain’s outside movement stopped, but his valve started to squeeze just a little bit, bringing Rumble within easy access of that spot, he started to lick and suckle at it, just barely scraping his teeth across it every now and again. At the same time he transformed his arms into their piledriver modes and set them to vibrate against the bottom of the valve, adding extra stimulus.

He heard Astrotrain cry out a strangled sounding “Yes, please-” and he knew he was on the right track. The valve trembled around him as Astrotrain’s inner workings tried their damndest to add more pressure to both areas. He complied with his piledrivers but Rumble kept his mouth work soft and un-rushed. He could feel the way Astrotrain was shifting from side to side, it made him think of the big triple-changer flinging his face back and forth as he tried to comprehend the pleasure he was feeling. 

Then it happened, everything stilled for just a moment and then tightened even more, trying to hold Rumble in place. Instead the flood of lubricant that crashed into him dislodged the cassette, pushing him back out of the valve with a soft plop as Astrotrain howled his climax. Rumble looked up and took an instant capture of the moment, Astrotrain bowed up off the berth held up by the top of his helm pressed to the wall and his feet while his hands held a death grip on the edges of the bed, his own cum splattered up his chest while his spike bobbed in place and his valve tried to squeeze down on nothing with lubricant dripping from it, some glittering on the inside of the thighs. 

Once the triple-changer lowered back down and relaxed some, though aftershocks still shook him he looked down at Rumble and Rumble looked back up at him. “So it was good, huh?” Rumble asked and he nodded, feeling a bit dumb for his lack of ability to iterate just how good. “Well I would be happy to do it again sometime...” the cassette continued, getting a hungry look of interest from Astrotrain “But... only if you help me out here too.” Rumble pointed down to his own spike which had been released as he had watched Astrotrain finish his climax.

Astrotrain just grinned and held out a hand. “That’s a deal.” When the cassette came close he grabbed hold of him and brought him up to his mouth. With just a little encouragement from his tongue he had Rumble’s hips between his lips and was tonguing him as Rumble did thrashing and howling of his own.

This was going to be a good exchange all around, he was sure of it.


End file.
